Control for heat pump



United States Patent Donald C. Ferdelman Dayton, Ohio Jan. 23, 1969 Nov.3, 1970 General Motors Corporation Detroit, Michigan a corporation ofDelaware Inventor Appl. No. Filed Patented Assignee CONTROL FOR HEATPUMP 4 Claims, 3 Drawing Figs.

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Field of Search References Cited UNlTED STATES PATENTS 3/1954 Ditzler etal.

3,173,476 3/1965 McCready 165/29 3,261,935 7/1966 Foster et al. 165/293,373,800 5/1968 Ferdelman 165/29 Attorney-Carl A, Stickel and w. E.Finken ABSTRACT: In the preferred form, a gang of six, six positionselector switches having a common selector operating means selectseither a heating cycle withmedinrn or high fan speed or a cooling cyclewith either low or medium or high fan speed. A stage type double throwthermostat switch controls the refrigeration system for both heating andcooling. A thermostatic heat changeover double-throw switch substitutesresistance heating for reversed cycle heating when the latter becomesless desirable. An additional switch on the stage thermostat energizesan added resistance heater upon a greater fall in temperature.

(JONTROL, FOR HEAT PUMP This invention is directed to an improvedcontrol system for reverse cycle air-conditioners.

In my U.S. Pat. No. 3,373,800, issued Mar. 19, 1968, l provide a controlfor a reverse cycle air-conditioner providing only one fan speed forheating and two fan speeds for cooling. This control also requires arelay for energizing the fan motor during heating. I

It is an object of this invention to provide an improved control systemfor a reverse cycle air-conditioner providing addi tional selections offan motor speeds for both heating and cooling and to eliminate the fanmotor relay mentioned in the previous paragraph.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein preferred embodiments of the present invention areclearly shown.

IN THE DRAWlNGS F l0. 1 is a wiring diagram illustrating my improvedcontrol system for a reverse cycle air-conditioning system embodying oneform of my invention;

FIG. 2 is a chart showing the closed positions of the various selectorswitches as "ON to perform the desired functions; and

FIG. .3 is a diagrammatic view of a reverse cycle air-conditioningsystem to which the control is applied.

Referring now more particularly to FIG. 3, there is showndiagrammatically a reverse cycle air-conditioning system including acompressor 20 having its outlet 22 connected to the reversing valve 24which in the position shown delivers the compressed refrigerant to theoutdoor heat transfer coil 26 which transfers heat from the refrigerantto the outdoor air. This transfer is greatly increased by the outdoorair fan 27 which is operated by the fan motor 36. The circulation of theoutdoor air in heat transfer with the outdoor coil 26 causes thecondensation of the compressed refrigerant which is forwarded throughthe restrictor 28 to the indoor heat transfer coil 30 where therefrigerant evaporates and absorbs heat from the air in the room to becooled. This absorption of heat is increased by the indoor fan 31 whichalso is driven by the fan motor 36 and which circulates air from theroom in heat transfer with the indoor coil 30. The evaporatedrefrigerant returns from the coil 30 through the reversing valve 24 tothe compressor inlet 32. The compressor 20 is driven by the compressormotor 84. The reversing valve 24 is operated to reverse position byenergizing a solenoid 34 which causes the compressor 20 to deliver thecompressed refrigerant through the reversing valve 24 to the indoor coil30 where it delivers heat to the room air circulated by the fan 31. Thiscauses condensation of the refrigerant which then flows through therestrictor 28 in the opposite direction to the outdoor coil 26 where itevaporates and absorbs heat from the outdoor air circulated by the fan27. The evaporated refrigerant then flows through the reversing valve 24to the inlet 32 of the compressor 20.

In FIG. 1, the supply conductor L1 connects to the movable contacts 11,12, 13 and 14 of a first gang of six position switches designated 1, 2,3, and 4. respectively. The switch 1 includes one contact below a seriesof five dead contacts which is connected by the conductor 90 to thelow-speed terminal 92 of the fan motor 36. The selector switch 2 has thesecond and sixth contacts connected by the conductor 135 with the mediumspeed terminal 137 of the fan motor 36. The No. 3 selector switch hasitsthird and fifth terminals connected by the conductor 94 to thehigh'speed terminal 96 of the fan motor 36. The fan motor 36 may haveany form of control desired to provide low, medium-and high-speedterminals. In the form shown, the motor 36 is provided with a mainwinding 196, a phase winding 197, the medium-speed winding 195 and alow'speed winding 192. A running capacitor 97 connects the phase windingterminal 98 with the second supply conductor 40 for improved phase shiftin both starting and running at all speeds; The junctions of themedium-speed winding 195 and the main winding 196 and the phase winding197 are connected at the high-speed terminal 96. With this arrangementlow-speed fan operation is provided in the lowest or full clockwiseposition, medium-speed operation is provided in the second and sixthpositions while high-speed operation is provided in the third and fifthpositions, with the fourth position having no connections for providingan OFF" position.

The supply conductor Ll also connects to the movable double throw switchmember 42 of the stage type thermostat 44 which is responsive to roomair temperatuke. This switch member 42 is of the snap action type and athigher room temperatures of the thermostat 44 such as, for example 78F,this contact 42 will be moved into engagement with an upper contact 46which is connected by a conductor M6 to the movable contact 5 of theselector switch 6 which has its first, second and third contactsconnected by the conductor 48 through the motor protector switch 80 andthe conductor 82 with the compressor motor 84 which drives thecompressor 20.

When the room temperature is lowered, for example to 72F., the lostmotion connection of the stage thermostat 44 will move the double-throwswitch member 42 into engagement with its lower contact 50 whichconnects through the conductor 52 to the movable contact 7 of theselector switch 8. The selector switch 8 has its upper fifth and sixthcontacts connected by the conductor 141 to the double throw thermostaticheat changeover snap acting switch 143. The supply conductor L1 alsoconnects through the movable contact 14 with the six position selectorswitch 4 having its fifth and sixth contacts connected through theconductor 121 with the solenoid 34 which is also connected by theconductor 123 to the second supplyconductor 40. All of the movablecontacts of the selector switches are interconnected for substantiallysimultaneous movement by the common operating means showndiagrammatically and indicated by the reference character 109. Thus,whenever the gang of six selector switches is in the fifth and sixthposition, the supply conductor L1 will be connected to the heatchangeover switch 143 and the reversing solenoid 34'. The heat transferswitch 143 is positioned in heat transfer with the outdoor air and inthe preferred form will remain in its lower position at outdoortemperatures above about 45F. In its lower position the snap action heatchangeover switch connects through the lower contact 149, the conductor145 and the auxiliary heater 147 which connects through the thermaloverload protector 80 with the compressor motor 84 and the outdoor fanmotor 29. The auxiliary heater 147 provides for quicker tripping of thethermal overload protector 80 during the reverse cycle operation forbetter protection of the motor.

When the temperature of the outdoor air falls below 45F., thesnap-acting thermostatic heat changeover switch 143 will snap upwardlyinto engagement with its upper contact 151 connecting with theresistance heater 153 which connects through the temperature safetyswitch 139 with the second supply conductor 40. This provides moreefficient heating at low outdoor air temperatures and prevents frostingthe outdoor coil. The resistance heater 153 lS associated with theindoor coil 30 so that it is in heat transfer with the indoor aircirculated by the fan 31.

The conductor 121 is connected by a branch conductor 58 to an additionalsnap actingmovable contact 54 of the stage thermostat 44. When thereverse cycle operation of the refrigerating system or the heater 153 isunable to maintain warm enough temperatures to satisfy the stagethermostat 44, a slight additional. fall in temperature will cause thesnap act ing switch 54 to move downwardly into engagement with thecontact 56. This contact connects through the conductor 60 with theauxiliary resistance heater 62 which also connects to the safetytemperature thermostat 139. The energization of this auxiliary heater 62provides additional heating sufficient to maintain the temperature ofthe room at the desired levels during extremely cold weather.

While the embodiments of the invention as herein disclosed constitutepreferred forms, it is to be understood that other forms might beadopted.

lclaim:

l. A reverse cycle refrigerating and control system including arefrigerant circuit provided with indoor and outdoor heat transfer unitsand a motor compressor unit provided with terminals and a flow controlmeans for controlling refrigerant flow between the indoor and outdoorheat transfer units and an electrically operated reversing valve havingterminals for changing the refrigerant connection between the motorcompressor unit and the indoor and outdoor units, a fan and multiplespeed fan motor having low-and medium-and high-speed terminals and afourth terminal for circulating indoor and outdoor air in heat transferwith said indoor and outdoor units, electric heater means and terminalsfor heating the circulating air, a double-throw heat changeover switchhaving a doublethrow switch member and having one alternate terminalcon- 1 nected to said heater means and having a second alternateterminal connected to a terminal of said motor compressor unit, a firstsupply conductor connected to said fourth terminal of said fan motor andto a terminal of said reversing valve and to a terminal of said heatingmeans and to a terminal of said motor compressor unit, a second supplyconductor, wherein the improvement comprises a first multiple selectorswitch means connected to said second supply conductor having a firstselective contact means individually connecting to said low-speedterminal and having a second selective contact means individuallyconnecting to said medium-speed terminal and having a third selectivecontact means individually connecting to said high-speed terminal ofsaid fan motor and having a fourth selective contact means individuallyconnecting to a terminal of said reversing valve, a stage-type dualthermostatic switch means having a double-throw switch member connectedto said second supply conductor and having first and second double-throwterminals and having a second switch with one terminal connected to aterminal of said reversing valve and another terminal connected to aterminal of said electric heater, and second multiple selector switchmeans having a first contact means connecting said first double-throwterminal with a terminal of said motor compressor unit and having asecond contact means connecting said second double-throw terminal tosaid double-throw switch member of said heat changeover switch.

2. A control system as defined in claim 1 in which interconnecting meansare provided for said first and second multiple selector'switch means,said selector switch means being providcd with one position closing onlysaid first contact means of said first selector switch means and saidfirst contact means of said second selector switch means and beingprovided with a second position closing only said second contact meansof said first selector switch means and said first contact means of saidsecond selector switch means and being provided with a third positionclosing only the third contact means of said first selector switch meansand said first contact means of said second selector switch means,

3. A control system as defined in claim 1 in which interconnecting meansare provided for said first and second multiple selector switch means,said selector switch means being provided with one position closing onlythe second and fourth contact means of said first selector switch meansand said second contact means of said second selector switch means andbeing provided with a second position closing only the third and fourthcontact means of said first selector switch means and said secondcontact means of said second selector switch means.

4. A control system as defined in claim 3 in which interconnecting meansare provided for said first and second multiple selector switch means,said selector switch means being pro' vided with three positions closingonly the first contact means of said second selector switch meanstogether with either the first or second or third contact means of thefirst selector switch means said selector switch means being alsorovided with two additional positions closing only the secon contactmeans of said second selector switch means together with either thesecond and fourth contact means or the third and fourth contact means ofsaid first selector switch means.

